1. Field of the Invention
The present invention relates to a robot hand which is provided with a palm and a plurality of fingers extended from the palm and which carries out an operation of holding an object by adjusting the position and the posture of the palm and by moving each of the plurality of fingers.
2. Description of the Related Art
A technique for controlling the movement of a finger mechanism, which is a constituent element of a robot hand, by using a medium of a gas or a liquid, such as oil, has been proposed (refer to Japanese Patent Application Laid-Open No. 2003-039370). The finer mechanism is mechanically connected to a first piston of a first cylinder, and the first cylinder is connected to a second cylinder through a pipe. The first piston is driven forward and backward as a second piston of the second cylinder is driven forward and backward, thereby driving the finger mechanism. The movement of the second piston is controlled on the basis of the pressure of a medium in the pipe. In order to secure the stabile control of the movement of the second piston, the pipe is made of a member that restrains the diameter of the pipe from changing even when the pressure of the medium in the pipe changes.
However, the pipe is preferably flexible to enhance the freedom degree of the layout of the pipe. On the other hand, a change in the diameter of a flexible pipe caused by a change in the pressure of the medium in the pipe may impair the stability of the control of the finger mechanism movement.
Further, there are cases where air getting into the pipe or the like prevents a fluid pressure generated by the second cylinder from being adequately transmitted to the first cylinder. This inconveniently makes it difficult to control the bending and stretching operation of the finger mechanism with high accuracy.